A clean cut surface with less thermal damage is typically desired in laser micromachining process. Many kinds of cooling substances can be employed to assist the laser ablation for limiting the thermal damage in workpiece and also gaining a higher material removal rate. This paper presents and compares the water- and ice-assisted laser ablation of titanium alloy, in which the effects of water/ice temperature, laser traverse speed and number of laser passes on morphology and dimensions of laser-ablated surface were experimentally investigated. A parametric model for the laser beam refraction at air-water/ice and water-gas bubble interfaces was also developed to determine the refracted distance at the workpiece surface under the different incident angles and water/ice layer thicknesses. The results revealed that the laser ablation in water can produce a clean groove on the metal surface, while only recast and spatters of titanium oxides were found on the laser-scanned track when processing in ice. A remarkable groove can be obtained by using high water temperature together with slow laser traverse speed and more numbers of laser passes. However, the laser beam scattering in water was more apparent than in ice due to water wave, the high refractive index of water and the formation of gas bubbles during the ablation. The findings presented in this study could provide a better understanding of the water- and ice-assisted laser ablation as well as their capability for damage-free fabrication of micro-/submicro-devices.

在激光微加工过程中通常需要具有较少热损伤的清洁切割表面。可以采用多种冷却剂来辅助激光烧蚀，以限制工件中的热损伤并获得更高的材料去除率。本文介绍并比较了水和冰辅助钛合金的激光烧蚀，其中实验研究了水/冰温度，激光移动速度和激光通过次数对激光烧蚀表面的形态和尺寸的影响。还建立了空气-水/冰和水-气泡界面处激光束折射的参数模型，以确定在不同入射角和水/冰层厚度下工件表面的折射距离。结果表明，在冰中加工时，水中的激光烧蚀可在金属表面上产生干净的凹槽，而在激光扫描的轨道上仅发现重铸和飞溅的二氧化钛。通过使用较高的水温以及较低的激光移动速度和更多的激光通过次数，可以获得明显的凹槽。然而，由于水波，水的高折射率和在消融期间形成气泡，激光束在水中的散射比在冰中更明显。这项研究中提出的发现可以更好地理解水和冰辅助激光烧蚀及其无损制造微型/亚微型设备的能力。在冰中加工时，在激光扫描的轨道上只发现了钛氧化物的重铸和飞溅。通过使用较高的水温以及较低的激光移动速度和更多的激光通过次数，可以获得明显的凹槽。然而，由于水波，水的高折射率和在消融期间形成气泡，激光束在水中的散射比在冰中更明显。这项研究中提出的发现可以更好地理解水和冰辅助激光烧蚀及其无损制造微型/亚微型设备的能力。在冰中加工时，在激光扫描的轨道上只发现了钛氧化物的重铸和飞溅。通过使用较高的水温以及较低的激光移动速度和更多的激光通过次数，可以获得明显的凹槽。然而，由于水波，水的高折射率和在消融期间形成气泡，激光束在水中的散射比在冰中更明显。这项研究中提出的发现可以更好地理解水和冰辅助激光烧蚀及其无损制造微型/亚微型设备的能力。由于水波，水的高折射率和烧蚀过程中气泡的形成，激光束在水中的散射比在冰中更明显。这项研究中提出的发现可以更好地理解水和冰辅助激光烧蚀及其无损制造微型/亚微型设备的能力。由于水波，水的高折射率和烧蚀过程中气泡的形成，激光束在水中的散射比在冰中更明显。这项研究中提出的发现可以更好地理解水和冰辅助激光烧蚀及其无损制造微型/亚微型设备的能力。